1. Field of the Invention
The invention is directed to an improved fuel injection device for an internal combustion engine and having a fuel pump for each cylinder of the engine.
2. Description of the Prior Art
A fuel injection device of this kind has been disclosed by EP 0 957 261 A1. For each cylinder of the engine, this fuel injection device has a fuel pump that has a pump piston that is driven into a stroke motion by the engine and delimits a pump working chamber to which fuel is supplied from a fuel tank. The pump working chamber is connected to a fuel injection valve that has an injection valve member, which controls at least one injection opening and can be moved in the opening direction, counter to a closing force, by the pressure prevailing in a pressure chamber connected to the pump working chamber. A first electrically controlled control valve is provided, which controls a connection of the pump working chamber to the fuel tank, which functions as a discharge chamber. A second electrically controlled control valve is also provided, which controls the control pressure prevailing in a control pressure chamber, which pressure acts at least indirectly on the injection valve member in the closing direction. In this known fuel injection device, it is disadvantageous that a fuel injection can only be carried out in accordance with the pressure level produced by the fuel pump.
The fuel injection device according to the invention has the advantage over the prior art that the third control valve and the pressure control valve permit a preinjection and a beginning of a main injection at a reduced pressure level, which can reduce the emissions and noise of the engine.